As for the inclusion of keywords (for SEO reasons) this is a massive no-no in professional copywriting circles. If you're writing for example a long form sales letter for online use, the last thing a pro copywriter will be concerned about is including the use of certain keywords.

The second you do this (in copywriting) you dilute the very purpose of the sales copy in question. Writing sales copy for online use has nothing to do with trying to get higher rankings in the search engines. It's number one purpose is to increase exponentially the conversion rate for whatever the direct call to action is.

I absolutely agree with these lines. It's easy to mistake copywriting for content writing, but the slight differences like ones you mentioned are what set copywriters apart from content creators.